2014 ''efficient'' tax exempt Insignia ''eco'' flex getting 35-40 mpg. listed as 63-88 mpg .

[Ready4it]

Hi.
I have owned a 2014 eco flex insignia for around 9 months. I have always been disappointed with the mpg it gets. I have given it a service but that hasn't improved anything . It has 98k on the clock now

the written mpg are as follows

urban - 62.3 mpg - I'm seeing 35- 38 mpg

combined - 77.4 mpg - I'm seeing 38 - 42 mpg !! ): mostly 40mpg

Extra urban - 88 mpg I'm seeing about 50 - 55 mpg solely motorway in 6'tyh gear with cruise control


I know the written mpg figures are always higher than real world but in previous experience my previous car's were about 10 mpg lower than what was written , not as much as 35 - 40 mpg difference that seems a gross exaggeration by the manufacturer !


I mostly drive urban with a few motorway trips and combined most often always returns 37- 40 mpg.
At first when I got the car my car was giving about 43 mpg around town but all of a sudden it dropped down to 35-38 mpg which even that I consider poor as most people with these cars say they get high 40's - early 50's around town and get about 700 - 750 miles a tank, yet I am barely scraping 500 miles a tank in this and it is a 70 litre tank !

I also fill it weekly brim to full, costs £85 but I feel I am only getting £50 or so from every fill up ( £85) out of it )

I recently drove it with an old tuning box my friend fitted but took it off after 25 miles as car was stalling and making chiming noises ( like seatbelt warning noise ) and lacking power. not sure if that caused decrease in mpg even after removing it because not long after fitting that and removing it I noticed a further drop in mpg ( it was already poor on fuel but became worse after )


I assume these car's are deemed efficient to be exempt from road tax, it's free road tax because low emissions and I assume low emissions means burns fuel slowly, yet this seems so heavy on fuel.
no idea at all why it is tax exempt considering how poor it is on fuel.

Any ideas greatly appreciated. thanks

 

[Ready4it]

after I bought the car I went to a different garage to get tyres fitted, guy did a free plug in on his diagnostic as told him I just bought it and could he check for anything on his reader make sure it is all ok , it had codes for cylinder misfires and glow plugs and fuel pressure regulator. The guy erased them and said most likely old codes. I am wondering if it could be something to do with that ? the car seems to drive without fault though.

Also when I put key in ignition a message shows briefly '' service vehicle soon' then goes out when I click the ok button. This was present when I bought the car which dealer said just means needs resetting after service but apparently it means an actual fault ?
not sure if that could have anything to do with the poor mpg, and if so what would likely cause a service vehicle soon display while the car seems it is running fine ?

 

[Burnerman]

All manufacturers MPG figures are hugely exaggerated.....if you can get around 55 on a motorway then thats fine but for general running expect around 43 or thereabouts.
However, a service could be a good idea which should include fuel and air filters, brakes being completely free and hard tyre pressures.
John

 

[Keithmac]

"Tested" mpg bears no relevance to real word driving.

I'm sure you don't get out of the car to push the brake pads back off the brake disks after every stop and that's just the tip of the iceberg..

A company a couple of years back did some proper real world testing including catching emissions while actually driving but I don't know if they are still active.

Basically anything you read in the brochure is bs..

 

[Harry Bloomfield]

The guy erased them and said most likely old codes. I am wondering if it could be something to do with that ? the car seems to drive without fault though.

Old codes are meaningless, there might have been an issue which was subsequently fixed, but the old codes not erased. The way to do it is - erase codes, drive it, rescan the fresh codes.

 

[Rad1o]

Be happy that the car is tax exempt. ALL car manufacturers are lying / fudging fuel consumption numbers.Some more than others.
When they test the cars, mirrors, seats, spare wheels, sunroofs have been removed, they role on tiny 155 section tyres - as long as that is legal -, rather than your standard 225ers. Air conditioning, radio, lights are all off to stop the generator from kicking in too much, which costs MPG.

 

[sxturbo]

give it a service ( a proper service not just an oil change, i can guarantee you the car sales wouldn't have serviced it properly, would just be an oil and filter change with the cheapest oil they can get their hands on, this is rarely the correct oil for the car also, and they would have just made sure that nothings loose or worn so you don't take it back under warranty)

run some injector cleaner through the tank.

check the codes haven't come back

diesels (and direct injection engines) have a tendency to clog up the intake ports and manifold with carbon deposits. this is mostly from the engine breathers. this has quit the bearing on mpg also.

sometimes the dpf gets partially blocked and reduces emissions also.

new cars can make close to their oficial figures but only for the first year or so, then they start reducing,

"How is MPG calculated?
There’s a common way MPG is calculated to give buyers a reliable way of comparing the economy of different cars.

Since the 1980s, the official way MPG was measured was called the New European Driving Cycle (NEDC). From 2017, this has gradually been phased out and replaced with the Worldwide Harmonised Light Vehicle Test Procedure (WLTP).

Like NEDC, the WLTP is laboratory-based. But the tests are designed to reflect real-life driving more accurately. This is because car owners have been complaining for years that the official manufacturer MPG figures are too high to be matched when driving on the road.

Nonetheless it’s very difficult to replicate everyday conditions such as wind direction and gradient. And even with WLTP it’s still very difficult for ordinary drivers to achieve official MPG figures."

 

[Harry Bloomfield]

diesels (and direct injection engines) have a tendency to clog up the intake ports and manifold with carbon deposits. this is mostly from the engine breathers. this has quit the bearing on mpg also.

That is more due to the EGR (exhaust gas recirculation) feeding oil from the turbo, back into the manifold/ just before the manifold, along with hot exhaust gases. The hot exhaust gasses, partially burn the oil on the internal surfaces and the intakes. It was a botch intended to improve the Nox emissions, which it did, at least until an engine got a few miles under it's bet, then it made them much, much worse than if it had never been fitted.

 

[cdbe]

Mate of mine had the same car, as company car, 6 months old, fully run in and he was getting 27mpg - he was an OCD type - logged all his mileage, receipts etc on a spreadsheet, had the car into Vauxhall to check everything. His previous Vectra recorded 44mpg. I think his deal was that he claimed a fixed pence per mile allowance for fuel so it was "costing" him and he kept trying to get the Vectra back.

 

[Harry Bloomfield]

My large diesel, still manages very respectable figures, because I sorted it and no, it ain't for sale.

 

[ericmark]

My wife had a Toyota Yaris and I had a Vauxhall Agila both same size cars, and makers claimed same miles per gallon, but the Toyota did far better than the Vauxhall and I just blamed the manufacturer for over stating what they can do.

However then we got a recall notice, seems the fuel tanks were springing a leak, at the top, so there was only a leak when full or moving, had it replaced and it sprung a leak again, so swapped a second time, but that is beside the point, it would seem a good idea to try with half full tank for a time.

Oddly it reminds me of problems with a Morris Minor, old lady complaining about performance and MPG, we tired to work out why, in the end we asked her to drive, didn't need to drive far, she hung her handbag on the choke.

Not saying your doing something silly, but do need to check things like tyre pressures, binding hand brake, etc. Even a wheel bearing. One would hope that is all done in a service, but good idea to ask them to check.

My wife and son both drive a Jaguar XE, hers should do more miles per gallon as the engine management is set so hers is 163 I think and his 195 however he always gets more than her, even when his is 4 wheel drive.

 

[Avocet]

Hi.
I have owned a 2014 eco flex insignia for around 9 months. I have always been disappointed with the mpg it gets. I have given it a service but that hasn't improved anything . It has 98k on the clock now

the written mpg are as follows

urban - 62.3 mpg - I'm seeing 35- 38 mpg

combined - 77.4 mpg - I'm seeing 38 - 42 mpg !! ): mostly 40mpg

Extra urban - 88 mpg I'm seeing about 50 - 55 mpg solely motorway in 6'tyh gear with cruise control


I know the written mpg figures are always higher than real world but in previous experience my previous car's were about 10 mpg lower than what was written , not as much as 35 - 40 mpg difference that seems a gross exaggeration by the manufacturer !


I mostly drive urban with a few motorway trips and combined most often always returns 37- 40 mpg.
At first when I got the car my car was giving about 43 mpg around town but all of a sudden it dropped down to 35-38 mpg which even that I consider poor as most people with these cars say they get high 40's - early 50's around town and get about 700 - 750 miles a tank, yet I am barely scraping 500 miles a tank in this and it is a 70 litre tank !

I also fill it weekly brim to full, costs £85 but I feel I am only getting £50 or so from every fill up ( £85) out of it )

I recently drove it with an old tuning box my friend fitted but took it off after 25 miles as car was stalling and making chiming noises ( like seatbelt warning noise ) and lacking power. not sure if that caused decrease in mpg even after removing it because not long after fitting that and removing it I noticed a further drop in mpg ( it was already poor on fuel but became worse after )


I assume these car's are deemed efficient to be exempt from road tax, it's free road tax because low emissions and I assume low emissions means burns fuel slowly, yet this seems so heavy on fuel.
no idea at all why it is tax exempt considering how poor it is on fuel.

Any ideas greatly appreciated. thanks

You don't say exactly what sort it is, but there are "real world" figures out there for many popular cars. Yours might be one of the ones listed here?

https://www.honestjohn.co.uk/realmpg/vauxhall/insignia-2008

Obviously your personal driving style has a huge influence too. In order to even get close to the "official" figures, you'd need to be driving like a nun who had overdosed on Horlicks!

Others have mentioned the disparity between "real world" and "lab" figures. I think "cheating" is maybe a bit of a strong word, but certainly manufacturers "optimise" their vehicles to get the best possible results in the lab. This is simply what happens when you introduce any kind of measurement-based rating system. Those being "rated" work out how best to play the system. It happens with teachers and exam results, hospitals and waiting list times, police and crime figures, etc. If anything, I see it as a failure of the regulatory system, rather than the manufacturers. The old NEDC drive cycle was nuts because it had to be achievable by the lowest powered cars on the market. This means your little 1000cc "shopping trolley" was actually working quite hard to achieve the required accelerations, while your Aston Martin would be doing it, virtually on a closed throttle! In the real world, of course, nobody buys an Aston and then drives it like a Fiat 500!

The New WLTP drive cycle goes some way to addressing this, by having three different drive cycles, depending on power-to-weight ratio. However, your Vauxhall wouldn't have been approved to the WLTP drive cycle. It wasn't around back in 2014.

 

[Avocet]

That is more due to the EGR (exhaust gas recirculation) feeding oil from the turbo, back into the manifold/ just before the manifold, along with hot exhaust gases. The hot exhaust gasses, partially burn the oil on the internal surfaces and the intakes. It was a botch intended to improve the Nox emissions, which it did, at least until an engine got a few miles under it's bet, then it made them much, much worse than if it had never been fitted.

I'm interested in this. In fact, it's something DfT are starting to look at more closely. It's very common practice to disable the EGR on older vehicles (for the reasons you state), but there don't seem to be any authoritative figures on the effect of EGR on NOx emissions in high mileage engines. Do you have any you'd be willing to share, please?

 

[Harry Bloomfield]

I'm interested in this. In fact, it's something DfT are starting to look at more closely. It's very common practice to disable the EGR on older vehicles (for the reasons you state), but there don't seem to be any authoritative figures on the effect of EGR on NOx emissions in high mileage engines. Do you have any you'd be willing to share, please?

I don't have any figures, it was just common sense to my mind, that an EGR + intake duct and intake ports choked up with carbon would be really bad news for both performance and consumption figures. I have seen EGR's so choked up with burned on oil and carbon, that they were down to 1/4 of the circumference of a new clean one.

They only come into operation at very low throttle opening/tick-over, developed to reduce NoX just at those times, as a quick easy fix, but with longer term implications for the engine health and emissions.

 

[Avocet]

I don't have any figures, it was just common sense to my mind, that an EGR + intake duct and intake ports choked up with carbon would be really bad news for both performance and consumption figures. I have seen EGR's so choked up with burned on oil and carbon, that they were down to 1/4 of the circumference of a new clean one.

They only come into operation at very low throttle opening/tick-over, developed to reduce NoX just at those times, as a quick easy fix, but with longer term implications for the engine health and emissions.

OK, thanks. My gut feeling, is that as long as the EGR valve isn't coked-up, it will work fine at reducing NOx. I've certainly seen clogged inlet manifolds and EGR valves on elderly diesels, but my pet theory, is that this happens on engines that aren't driven hard enough. Without doubt, admitting hot, sooty air to oil mist makes things worse, but if driven at maximum power for a few minutes each month, I think the effects are mitigated. My wife used to run a T30 X-Trail, and it was a common topic of debate on the owners' forum, with some real horror stories showing photos of inlet runners that you'd be lucky to fit a pencil down. Worried that the same must have been happening to our car, I took the manifold and EGR valve off at 100,000 miles, and was surprised to see a very light coating of sooty gunk in there, but that was about all!

My theory, is that the crank case fumes and (in later life) whatever gets past the turbo seals, find their way into the inlet tract. At this point, they're just thick, slightly sooty oil. This gunge coats the walls of the inlet duct, including all the intercooler tubes. Running the engine at max. power, gets the airflow through the inlet tracts up to a maximum and (I believe) "scours" this stuff off the surfaces and into the cylinders, where it gets burned. Normally, Mrs Avocet drives quite gently, but I'd make a point of borrowing it at least once a month, and "giving it death" up a long steep hill a few times. The first time I'd do it, the car would smoke a fair bit (no DPF on it) and the second time, there would be less smoke. If this isn't done regularly, the hot EGR gas "bakes" it on to the inlet manifold wall, and you get the buildup you describe.

A couple of years ago, I was given my sister's 140,000 mile, 2001 Freelander 1, as she was going to scrap it, having had it fail its MOT on (among other things) smoke. I took the inlet manifold off and sure enough, it was as you describe. She hates revving engines because she thinks it "hurts" them. I was scooping this gunge out with a teaspoon, lollipop stick, you name it!

Sadly, I never got round to taking a photo before I started, but there was a lot more than this!

That, on its own, (well, and a couple of good thrashings up my hill at 4500 revs on a wide open throttle), was sufficient to get the smoke readings way down to something a lot more respectable:

20,000 miles later, I took the inlet manifold off again, and there was no build-up of sooty gunge. I appreciate the previous lot was 140,000 miles worth, but I thought it was encouraging.